Cant hold temperature

Yesterday and Today i printed some parts with Nylon CF15.
Nozzle Temp 270°C
Bed Temp (inner zone) 110°C

Results are fine, but i noticed, if the snapmaker gets warm - it cant hold the build plate temperature.
First it reaches 110°C, but later goes down to 105/106.

Enclosure inside Temp is around 36 - 40°C

If i measure the inner zone temperature on the build plate with a infrared thermometer i have on the left side aorund 100°C and on the right side up to 128°C

Does anybody have the same experience or tips for improvements?

Are you actually printing when the bed temperature droops? I have found that the fans on the dual extruder (I’m on a Snapmaker 2.0) cool the bed below its ability to heat it when the head is hovering around the center of the bed (i.e. when printing a small object) during the first layer or two. I found I could improve this by attaching a flat deflector plate to the bottom of the extruder to stop air wafting down onto the bed. But I was only dealing with a bed temperature set point of 65c (the temperature would droop to 58c and then recover).

Yes, it is while printing. Part cooling fan at 100% at height 5mm for this part.
Sounds plausible that the fan cools down the heating bed, i’ll have to observe this more closely.